Field of the Invention
The present invention relates to a wiper blade for cleaning windows of motor vehicles and, more particularly, to a wiper blade comprising an elongated, rubber-elastic wiper strip provided with respective longitudinal grooves on its corresponding long sides, a support element for the wiper strip with corresponding spring rails engaged in and protruding from the longitudinal grooves and a connecting device for a wiper arm connected to a middle portion of the support element.
In wiper blades of the prior art, the support element is meant to assure the evenest possible distribution of the wiper blade contact pressure on the window over the entire swept field swept by the wiper blade. By means of a suitable curvature of the unstressed support elementxe2x80x94that is, when the wiper blade is not applied to the windowxe2x80x94the ends of the wiper strip, which in wiper blade operation are pressed entirely against the window, are urged toward the window by the then stressed support element, even if the radii of curvature of the spherically curved vehicle window differs in every position of the wiper blade. The curvature of the wiper blade must accordingly be somewhat greater than the greatest curvature of the swept field of the window to be wiped. The support element thus replaces the complicated support bracket construction, having two spring rails disposed in the wiper strip, of the kind employed in conventional wiper blades (German Patent Disclosure DE-OS 15 05 379).
In a known wiper blade of this type (German Patent DE-PS 10 28 896), with an attendant buildup of overpressure, the wiper blade can be engaged from below, on the front side facing into the wind, by this overpressure. On the other hand, on the backside facing away from the wind, a considerable negative pressure builds up. Although the wiper blade, which during operation usually executes a pendulum motion, constantly changes its position relative to the oncoming relative wind, even then one of its long sides is always more or less greatly exposed to the wind and is therefore called the front side, while its other long side is accordingly also thought of as the back side. At relatively high vehicle speeds, given the cooperation of these two aforementioned pressures, both of which are oriented counter to the wiper blade contact pressure, this contact pressure is reduced at least enough that proper wiping is no longer possible. Increasing the wiper blade contact pressure against the window at high vehicle speeds could admittedly reduce the severity of this problem, but at lower vehicle speeds, when the liftoff tendency is less, the friction between the wiper blade and the window increases; this leads to undesirable noise buildup and to excessively high stress on the drive components and on the rubber of the wiper. To suppress the aforementioned tendencies of the wiper blade to lift off from the window, the accessories trade offers so-called spoilers, which can be disposed on the wiper blade and support bracket system. With the wiper blade in question, however, this cannot be done, because fastening what is as a rule a rigid spoiler to the support element would render the flexibility of the support element virtually nil, making proper cleaning of the prescribed swept field no longer possible.
It is an object of the present invention to provide an improved wiper blade that does not have the above-described disadvantages.
According to the invention the wiper blade comprises an elongated, rubber-elastic wiper strip provided with respective longitudinal grooves on corresponding opposite long sides thereof and with a wiper lip for contact with a window; an elongated spring-elastic support element having spring rails engaged in and protruding from the longitudinal grooves provided in the wiper strip; a connection device for a wiper arm connected to a middle portion of the support element, wherein the spring rails have respective longitudinal edges extending outside of the longitudinal grooves and the connection device fits on the respective longitudinal edges to retain and hold the spring rails in the longitudinal grooves; a wind deflector strip comprising at least one longitudinal portion of the wiper strip located on a side of the spring rails opposite from the wiper lip and retaining means engaging opposite end portions of the spring rail.
In the wiper blade, via the leading-edge face of the wind deflector strip that faces into the wind, a force component aimed at the window is built up, which counteracts the liftoff tendency of the two pressures and thus assures excellent cleaning quality, at least in the region of the swept field swept by the wiper blade, that is, the region that is important to the vehicle""s driver. Depending on the size of the leading-edge face, this xe2x80x9cauxiliary contact pressurexe2x80x9d can be adapted to the variable demands that depend for instance on the type of vehicle. It is also advantageous in the arrangement of the invention that as a function of the vehicle speed, the contact pressure rises or falls with this speed. Thus a suitably high xe2x80x9cauxiliary contact pressurexe2x80x9d is opposed only to the liftoff tendency that occurs at high speed. At the same time, the longitudinal edges of the spring rails that protrude from the longitudinal grooves of the wiper strip offer an excellent capability of positioning and fastening the connection device.
If along its length the wind deflector strip has at least one recess, extending nearly to the longitudinal grooves, which serves to receive retaining means, disposed crosswise to the length, for the two spring rails, then the retaining means can become operative near their retention/attachment points, thus making undesirable leverage effects avoidable.
The part of the wiper strip embodied as a wind deflector strip expediently has a substantially triangular cross section, whose side facing into the wind is scooped out in concave fashion; the second side of the wind deflector strip is oriented essentially perpendicular to the window, and the third side, to form a wind deflector strip of compact design, forms the one groove wall, facing away from the window, for the spring rails.
Advantages from a manufacturing standpoint can be obtained if the wiper strip has a constant cross section substantially over its entire length.
To stabilize the wiper blade, the spring rails that belong to the support element can be engaged by a plurality of retaining means distributed over the length of the spring rails.
In this respect, further advantages from the standpoint of mounting and assembly are obtained if the connection device is embodied as retaining means.
An especially simple form of the further retaining means is obtained if these retaining means are embodied as clamps, which with claws on their ends reach around the spring rails on the longitudinal edges facing away from one another.
On the two ends of the wiper blade, mounting the retaining means becomes easy if the spring rails have their end portions exposed, and also if clamplike retaining means engage these end portions.
Further advantageous refinements and features of the invention are recited in the ensuing description of an exemplary embodiment shown in the accompanying drawing.